In prior art systems for treating soil and turf by blowing and/or vacuuming through a duct network located underneath the turf, a low-pressure high-volume fan is typically used to move air into the soil profile or remove moisture from the soil profile. U.S. Pat. Nos. 5,433,759; 5,507,595; 5,542,208; 5,617,670; 5,596,836; and 5,636,473, the disclosure of each of which is incorporated herein by reference in its entirety, show different variations on equipment used for this purpose. Since a non-reversing fan always rotates in the same direction, changing the system from a blowing function to a vacuuming function requires disconnecting the duct network from the blowing outlet of the fan unit and connecting it to the vacuum inlet of the unit. In some variations, a 4-way valve is used to avoid the hassles involved with selectively connecting and disconnecting the duct network from the various ports of the fan unit. Manual operations limit the degree to which the process can be automated. In addition, considerable judgment is involved in knowing when to blow air into the duct network and when to remove air from the duct network by applying a partial vacuum. Blowing air into the duct network when there is too much moisture in the soil profile can severely damage parts of the turf.
More recently, U.S. Pat. No. 6,273,638, the disclosure of which is incorporated herein by reference in its entirety, disclosed additional features of an air handling system that includes an air handling device connectable to a duct network that is underneath a field having grass growing in it, at least one sensor disposed to measure a variable associated with the field, and a control unit connected to the air handling device to control operating parameters of the air handling device responsive to an output from the sensor. A heat exchanger is optionally part of the system. The variables associated with the field include temperature and moisture. The operating parameters of the air handling device include direction of the air flow, temperature of the air directed into the duct network, and the time of operation of the unit. The system optionally includes programmable control logic so that the sensor output automatically controls the operating parameters of the system. A computer with display is used to program the control logic, which can be done remotely over a modem or the internet. The sensor output can be viewed on the display to allow a user to manually control the operating parameters if desired.
What is lacking are systems that can be operated where power supplies have insufficient capacity, and systems that can handle a diversity of environmental parameters over disparate areas of interest.